The invention relates to improvements in apparatus for removing surplus from a stream of particles of natural, reconstituted and/or substitute tobacco, hereinafter referred to as tobacco. More particularly, the invention relates to apparatus for removing surplus from a stream which is being transported by a pneumatic conveyor, for example, from the distributor (also called hopper) to the wrapping mechanism of a tobacco rod making machine.
The distributor of a rod making machine (such as a cigarette rod maker) is constructed and assembled to deliver at least one continuous stream of tobacco particles to a pneumatic conveyor, such as a conveyor which includes an endless foraminous belt, means for driving the belt, and a suction chamber adjacent one side of an elongated reach or stretch of the belt so that the particles of tobacco forming a stream are attracted to the other side of the reach or stretch and are advanced to a mechanism wherein successive increments of the stream are confined in a continuous web of suitable wrapping material, such as cigarette paper. The stream which issues from the distributor contains a surplus of tobacco particles, and such surplus is removed by a trimming mechanism so that the remainder of the stream (called filler) constitutes a continuous rod which advances through the wrapping mechanism to emerge in the form of a cigarette rod ready to be subdivided into rod-shaped articles of unit length or multiple unit length. The stream is normally obtained by showering tobacco particles onto or against the other side of the aforementioned stretch or reach of the foraminous belt. Such stream contains a surplus of particles because this ensures that, after trimming, each unit length of the filler contains the same quantity or a desired quantity of tobacco particles. It is also known to densify longitudinally spaced apart portions of the stream so that the corresponding portions of the filler contain more tobacco than the portions between successive densified portions. Such procedure is adhered to if the maker is to turn out plain cigarettes, cigars or cigarillos with dense ends. If a rod-shaped article of the tobacco processing industry is provided with one or two dense ends, it is less likely to lose particles at the dense end or ends, e.g., during storage, during transport to a packing machine, during transport to a filter tipping machine or subsequent to opening of a packet containing a number of parallel smokers' products.
Heretofore known trimming or equalizing mechanisms which are used to separate the surplus from the remainder of a tobacco stream upstream of the wrapping station normally comprise a pair of discs which clamp successive increments of the stream between the surplus and the major portion of the respective increment of the stream, and a surplus removing tool, such as a paddle wheel, which brushes or sweeps the surplus at those sides of the discs which face away from the major portion of the stream. Reference may be had, for example, to U.S. Pat. No. 4,210,159.
It is also known to remove the surplus by resorting to a milling tool which is oriented in such a way that it acts not unlike a paddle wheel, i.e., the tool sweeps the surplus away from the remainder of the stream. Such milling tool is disclosed in the published German patent application No. 29 49 494.
A drawback of the trimming mechanisms which employ a paddle wheel or a milling tool is that the rapidly orbiting paddles or cutting edges not only remove the surplus from the remaining (equalized) portion of the stream but also subject the removed surplus to an undesirable comminuting action. The orbiting paddles of a wheel or the orbiting cutting edges of a milling tool actually tear the surplus off the major portion of the moving stream and propel the thus separated and comminuted particles away from the clamping discs. This reduces the quality of the removed surplus as well as of the rod-shaped articles because the removed surplus is reintroduced into the distributor and is admixed to tobacco which is showered onto or against the aforementioned foraminous belt. Moreover, heretofore known trimming mechanisms cannot ensure that all or practically all particles of the removed surplus can be gathered for predictable reintroduction into the distributor of a tobacco rod making machine, such as a cigarette maker.